Packaging design for a flow sensor and methods of manufacturing thereof

Abstract

Disclosed herein are embodiments of a sensor assembly, methods of manufacturing the same, and methods of using the same. In one embodiment, a sensor assembly comprises a substrate comprising an outer region, an inner region, and a middle region positioned between the outer region and the inner region, the substrate further comprising electrical contact pads on at least the inner region. The sensor assembly further comprises a housing coupled to the substrate at the outer region or at the middle region to form a hermetic seal. The sensor assembly further comprises a sensor device coupled to the substrate, via the electrical contact pads, at the inner region. In certain embodiments, the sensor assembly further comprises a conformal coating deposited on at least a portion of the sensor assembly.

What is claimed is: 
     
       1. A sensor assembly comprising:
 a multi-layered ceramic substrate comprising an outer region, an inner region, and a middle region positioned between the outer region and the inner region, the multi-layered ceramic substrate comprising electrical contact pads extending from the outer region to the inner region between a first ceramic layer and a second ceramic layer; 
 a housing coupled to the substrate at the middle region to form a hermetic seal; and 
 a sensor device coupled to the substrate, via the electrical contact pads, at the inner region. 
 
     
     
       2. The sensor assembly of  claim 1 , further comprising a conformal coating deposited on at least a portion of the sensor assembly. 
     
     
       3. The sensor assembly of  claim 1 , wherein the sensor device comprises a free-standing sensing element coupled to a support structure, and wherein the sensor device is secured to the substrate such that the support structure is in parallel orientation relative to a gas flow direction. 
     
     
       4. The sensor assembly of  claim 1 , wherein the housing comprises a gas-facing surface and an opposing surface opposite the gas-facing surface, wherein the housing has a slot formed therethrough, and wherein the substrate is disposed in the slot in a cantilever orientation such that the inner region of the substrate extends from the gas-facing surface and the outer region of the substrate extends from the opposing surface to an exterior region. 
     
     
       5. The sensor assembly of  claim 4 , wherein the middle region of the substrate comprises a first surface and a second surface opposite the first surface, wherein the first surface is secured to the opposing surface of the housing in a parallel face-to-face configuration, and wherein an o-ring is disposed between the substrate and housing. 
     
     
       6. The sensor assembly of  claim 5 , wherein the sensor device is coupled to the electrical contact pads via a first seal, and wherein the first surface is secured to the opposing surface of the housing via a second seal. 
     
     
       7. The sensor assembly of  claim 6 , wherein the first seal and the second seal independently comprise Al alloy, Ag alloy, Au alloy, Ni alloy, Si alloy, Au—Ni alloy, Ni—Pd alloy, Ni—Y alloy, Ti alloy, or a combination thereof,
 wherein the electrical contact pads comprise one or more conductive metals, and 
 wherein the housing comprises stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-ferrous alloy, or a combination thereof. 
 
     
     
       8. The sensor assembly of  claim 5 , further comprising a flange secured to the opposing surface of the housing, and wherein the first surface of the middle region of the substrate is secured to the flange in a parallel face-to-face configuration. 
     
     
       9. The sensor assembly of  claim 8 , wherein the sensor device is coupled to the electrical contact pads via a first seal, wherein the flange is secured to the opposing surface of the housing with welding, and wherein the first surface is secured to the flange via a second seal. 
     
     
       10. The sensor assembly of  claim 9 , wherein the housing has a first coefficient of thermal expansion (CTE 1 ), wherein the substrate has a second coefficient of thermal expansion (CTE 2 ), and wherein the flange has a third coefficient of thermal expansion (CTE 3 ), and wherein CTE 3  is between CTE 1  and CTE 2 . 
     
     
       11. The sensor assembly of  claim 9 , further comprising a back-up ring positioned between the flange and the opposing surface of the housing, wherein the back-up ring comprises a housing facing surface and a flange facing surface opposite to the housing facing surface, and wherein the flange is secured to the flange facing surface of the back-up ring via a third seal. 
     
     
       12. The sensor assembly of  claim 11 , wherein the first seal, the second seal, and the third seal independently comprise Al alloy, Ag alloy, Au alloy, Ni alloy, Si alloy, Au—Ni alloy, Ni—Pd alloy, Ni—Y alloy, Ti alloy, or a combination thereof,
 wherein the electrical contact pads comprise one or more conductive metals, and 
 wherein the housing and the flange independently comprise stainless steel, a nickel alloy, a nickel-chromium-molybdenum alloy, a nickel-cobalt-ferrous alloy, or a combination thereof, 
 wherein the back-up ring comprises a ceramic. 
 
     
     
       13. A flow control apparatus comprising:
 a gas flow channel defining a gas flow path; 
 a flow modulating valve configured to modulate gas flow in the gas flow channel; 
 a sensor assembly coupled to the gas flow channel, the sensor assembly comprising:
 a substrate comprising an outer region, an inner region, and a middle region positioned between the outer region and the inner region, the substrate further comprising electrical contact pads extending from the outer region to the inner region between a first ceramic layer and a second ceramic layer; 
 a housing coupled to the substrate at the middle region or at the outer region to form a hermetic seal; 
 a sensor device coupled to the substrate, via the electrical contact pads, at the inner region; and 
 a conformal coating deposited on at least a portion of the sensor assembly; and 
 
 a processing device operatively coupled to the flow modulating valve and the sensor device, the processing device being configured to adjust the flow modulating valve based on signals received from the sensor device.